(1) Field of the Invention
The invention relates to a gas-liquid mixing device, forming a safety valve, designed capable of being incorporated into a gas-cleaning installation including a liquid tank, an inlet for the gas to be cleaned and an outlet through which the gas flow is evacuated.
It also relates to a gas-cleaning installation provided with such a gas-liquid mixing device.
It also relates, in particular, to a vacuum cleaner with water filtering provided with such a gas-liquid mixing device.
The invention relates to the field of the cleaning treatment of gases, in particular air, in industrial or household applications.
Among the latter, the traditional vacuum cleaners with water filtering include a suction device which drives an air flow loaded with debris through a tank containing water. The filtering of the impurities occurs in this water through bubbling, then the air is evacuated towards the outside after passing through a water-air separator system and after passing through the suction block.
The vacuum cleaners with water filtering have several important advantages over the traditional vacuum cleaners having filter bags, or various filters interposed in the gas-circulation circuit, and namely:                Such vacuum cleaners have a constant suction power for a longer period of time, according to the additional filters used, compared to the traditional vacuum cleaners, in which the filter device clogs as the use and filling of the waste-containing bag progresses.        A vacuum cleaner with water filtering can eventually also be without any additional filter to be periodically replaced or cleaned.        A vacuum cleaner with liquid filtering including no bag, the user does therefore not have to buy consumables and the maintenance of the appliance is limited.        The traditional vacuum cleaners do not allow the suction of water and cannot be used for this recovering function.        The use of disinfectant, deodorant or essential oils in the bubbling water of the vacuum cleaner with liquid filtering provides additional functionalities as compared to the traditional vacuum cleaners and in particular the possibility of eliminating acarids.        A vacuum cleaner with water filtering also allows humidifying the air, which can sometimes be desired.        
The vacuum cleaners with water filtering allow the cleaning of all floors, carpets, moquettes, textiles, and the like, in the same manner as the traditional vacuum cleaners having filters in the form of bags, cyclone systems, or also specific filters.
(2) Description of the Prior Art
The main technical difficulties met in developing the vacuum cleaners with water filtering is due to the fact that, in a first step, a very intimate mixing must be performed between the air loaded with debris and the water of the vacuum cleaner, then, when said debris are trapped in the water, an as effective as possible separation of the water must be performed, before the passing through the suction module and before the rejection into the atmosphere of the room, in order to remove the droplets in suspension from the gas flow.
Furthermore, the vacuum cleaner must include an overflow safety, in order to avoid, when the vacuum cleaner sucks up water, the complete filling of the tank from driving liquid towards the outlet of the vacuum cleaner. This overflow safety is usually brought about by means of a floating body, often in the form of a ball, enclosed in a cage.
EP 0 768 058 describes such a device, which uses, right from the entering of an air flow loaded with debris, the venturi effect in order to humidify these debris with water contained in a tank, and which includes, on the path of this air loaded with debris and water, before its passing through an air-water separator and suction means, a container provided with such an overflow float. This device has however the drawback of reacting too quickly in an air flow with a high flow-rate, which causes unexpected stoppages of the vacuum cleaner.